This specification incorporates Australian Provisional Patent Application No. 2010904627 filed on 16 Oct. 2010 and Application No. 2011900806 filed on 7 Mar. 2011 and incorporates all aspects of those documents and the invention disclosed therein. The present specification, drawings and claims are improvements upon and refinements of the invention disclosed in Application Nos. 2010904627 and 2011900806.
The reinstatement of excavated materials from civil or mining engineering works is an activity that is both time and labour intensive. Reinstatement works are expensive as a result of associated labour costs and the costs of preparing excavated materials for reinstatement. Costs associated with the storage and maintenance of plant equipment and the excavated materials themselves are high, particularly in circumstances where a particular blend of materials is required to effect proper reinstatement of a surface.
Transportation costs are also prohibitive with many reinstatement works or projects.
Reinstatement works typically involves the removal of the excavated materials and the transportation of graded aggregates to the reinstatement site. It is usual practice to add a stabilising agent to the graded aggregates in order to provide a stable surface once reinstatement works have been completed. There are problems associated with the onsite preparation of graded aggregates and stabilising agents including the need to have available plant on site to perform the processing of the stabilising agent and aggregate. Typically therefore it is necessary to process and store aggregate materials off site and to transport said materials to the reinstatement work site. This method is both expensive and results in additional resources being required, for example, plant and fossil fuels.
Aggregate and stabilising agent must be maintained at a constant temperature to prevent solidification of the materials prior to placement upon the reinstatement site. Previous devices have failed to address this important aspect of reinstatement works. It has been shown that the use of friction alone through agitating or mixing materials is insufficient in regions where external temperatures are low, in particular, at temperatures below freezing. In such circumstances it is necessary to also apply heat to the materials to ensure the viscosity of the aggregate mixture and utility of the materials when dispatched.
Devices and vehicles which have been designed to enable the recycling of excavated materials and delivery of same with a suitable stabilising agent on site are known in the prior art. PCT/GB2009/050076 of Balfour Beatty describes a suction recycling arrangement which offers one such solution which incorporates the use of suction for the removal of excavated materials and apparatus for blending the materials with a stabilising agent. The proposed solution of PCT/GB2009/050076 suffers from several disadvantages in practical application, for example the time which is necessary to process the excavated materials prior to reinstatement. The Balfour Beatty solution has an additional problem in that it requires a constant electrical power source to enable the high velocity suction necessary to enable the apparatus to operate.
The laying of asphalt, for example, requires the use of tar which is mixed with sand and graded aggregate as a stabiliser to make road surfaces. It is necessary to use tar in its liquid form which requires the application of constant heat to prevent solidification of the reinstatement materials. Other devices which have been developed for the transportation of reinstatement materials to work sites include hot boxes which include heating elements within them for maintaining a constant temperature in order that the reinstatements materials housed within them do not solidify and become unusable. In use, these hot boxes require the user to constantly add aggregate materials to the hot box for mixing prior to placement at the reinstatement site. These additional materials must either be transported to the site upon a vehicle upon which the hot box is mounted or by separate vehicles which may or may not hold aggregate materials of different grades. Additional transportation costs and fuel are inevitable with the use of hot boxes as they are known in the art presently.
In traditional methods of reinstatement works, there is much wastage as materials become unusable once they solidify. It would therefore be desirable to provide a means whereby the materials can be constantly heated in order to prevent such wastage.
It would also be advantageous to provide an apparatus and method for means for preparing and delivering road surface reinstatement materials which could be used in sub-zero environments with minimal wastage.
A further problem associated with heating and transporting such materials is the requirement to use large quantities of petroleum fuels to transport materials to work sites and for the maintenance of heat to prevent wastage.
It would be useful or advantageous therefore to provide an apparatus and method for delivering to a reinstatement work site a premixed graded aggregate and stabilising agent blend which will be suitable for use at the site and which will increase the speed of delivery of the materials and the processing of the work and which would enable the prevention of wastage of materials.
It would be also advantageous to provide a method for the preparation and delivery of reinstatement materials to a work site that reduces the volume of fuel required for transportation, and where such fuel savings could be translated into or equate to carbon credits and so be readily accepted in new environmentally friendly economic models.